Bone morphogenetic proteins (BMPs) belong to the TGF superfamily. BMPs bind to specific type-I and -II serine/threonine kinase receptor complexes, RIa, RIb, and RII, which signal through SMAD proteins or the p38 mitogen-activated protein kinase (MAPK). The BMPs are important regulators of key events in many aspects of tissue development and morphogenesis, including the processes of bone formation during embryogenesis, postnatal growth, remodeling and regeneration of the skeleton. Localization studies in both human and mouse tissues have demonstrated high levels of mRNA expression and protein synthesis for various BMPs in adipose, heart, lung, small intestine, limb bud and teeth.
Several BMPs have been implicated in early skeletal development, including BMP-2, -4, -5, -7, -14 (CDMP-1 /GDF-5). Other members, such as BMP-3, -6, -7 and -13 (CDMP-2/GDF-6) may be involved in later stages of skeletal formation.